The purpose of the research is to determine the role of hypothalamus in the control of secretion of tropic hormones by the anterior pituitary and to investigate the role of such biogenic amines as the catecholamines and indoles on the secretion of hypophysiotropic substances into hypophysial stalk portal blood. Biogenic amines will be given by way of the third ventricle and by means of microelectrophoresis. Secretion rates of hypophysiotropic substances will be determined by collecting pituitary stalk blood. The response of the anterior pituitary in vivo to hypophysiotropic substances will be determined by infusion of these substances into a hypophysial portal vessel.